OHAUS DISCOVERY BALANCE User manual

SERVICE MANUAL
DISCOVERY BALANCE
Ohaus Corporation 19A Chapin Road, P.O. Box 2033, Pine Brook, NJ 07058-2033 [phone]

SERVICE MANUAL
DISCOVERY BALANCE
The information contained in this manual is believed to be accurate at the time of publication, but Ohaus
Corporation assumes no liability arising from the use or misuse of this material. Reproduction of this
material is strictly prohibited.
Material in this manual is subject to change.
© Copyright 2007 Ohaus Corporation, all rights reserved.
TM Registered trademark of Ohaus Corporation.

TABLE OF CONTENTS
Page No.
CHAPTER 1 INTRODUCTION
1.1 Introduction................................................................................................................1-1
1.2 Service Facilities........................................................................................................1-1
1.3 Special Tools and Test Equipment Required ............................................................1-2
1.4 Test Masses Required...............................................................................................1-3
1.5 Specifications.............................................................................................................1-4
CHAPTER 2 DIAGNOSIS
2.1 Troubleshooting.........................................................................................................2-1
2.2 Diagnosis Guide ........................................................................................................2-1
2.2.1 Diagnosis............................................................................................................2-1
2.3 Table of Error Codes ................................................................................................2-6
CHAPTER 3 REPAIR PROCEDURES
3.1 Repair Procedures.....................................................................................................3-1
3.1.1 Housing Disassembly/Opening the Balance ......................................................3-2
3.1.2 Display Removal & Replacement.......................................................................3-5
3.1.3 Main Printed Circuit Board (PCB) Removal & Replacement..............................3-8
3.1.4 Incal Weight Hardware Disassembly................................................................3-10
3.1.5 Removing and Replacing Calibration Motor Assembly ....................................3-13
3.2 Load Cell Cover Removal and Disassembly ...........................................................3-15
3.2.1 Load Cell Removal ..........................................................................................3-15
3.2.2 Load Cell Disassembly.....................................................................................3-20
3.2.3 Load Cell Cleaning...........................................................................................3-30
3.2.4 Load Cell Assembly .........................................................................................3-31
3.2.5 Installing Load Cell...........................................................................................3-45
CHAPTER 4 TESTING
4.1. Testing.......................................................................................................................4-1
4.1.1 Operational Test.................................................................................................4-1
4.1.2. Models Segment Display Test............................................................................4-1
4.2. Load Cell Performance Tests....................................................................................4-1
4.2.1 Off-Center Load Test..........................................................................................4-1
4.2.2 Adjusting Off Center Load..................................................................................4-2
4.2.3 Repeatability Test...............................................................................................4-4
4.2.4 Remediation .......................................................................................................4-4
4.2.5 Linearity Test......................................................................................................4-5
4.3 RS232 Interface Test.................................................................................................4-6
4.4 RS232 Connection.....................................................................................................4-6
4.4.1 Connecting the RS232 Interface ........................................................................4-6
4.4.2 RS232 Commands.............................................................................................4-8
4.5 Print Test ...................................................................................................................4-9
4.6 Testing the AC Adapter .............................................................................................4-9
CHAPTER 5 PARTS LISTS & DIAGRAMS
5.1 Discovery Housing.....................................................................................................5-1
5.2 Discovery Display Assembly......................................................................................5-2
5.3 Discovery Internal Parts Outside Load Cell...............................................................5-3
5.4 Discovery Load Cell Parts .........................................................................................5-4
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TABLE OF CONTENTS
Page No.
Appendix A STANDARD CALIBRATION
A.1 Automatic Internal Calibration (Advanced Auto Cal) ................................................ A-2
A.2 Span Calibration....................................................................................................... A-3
A.3 Calibration Test (Cal Test)........................................................................................ A-4
A.4 Calibration Adjustment (Cal Adj)............................................................................... A-5
Appendix B SERVICE CALIBRATION
B.1 Navigation................................................................................................................. B-1
B.2 Entering Service Menu ............................................................................................. B-1
B.3 Ramp........................................................................................................................B
-2
B.4 Service Span Calibration.......................................................................................... B-3
B.5 Service Internal Calibration (InCal)........................................................................... B-4
APPENDIX C SOFTWARE SERVICE TOOL INSTRUCTIONS
C.1 Restore EEPROM Data............................................................................................ C-2
C.2 Replace Load Cell ....................................................................................................C-3
C.3 Install new Main Printed Circuit Board......................................................................C-4
C.4 Update Software in the Balance...............................................................................C-5
C.5 Diagnostics...............................................................................................................C-6
C.5.1 Incal Weight Mechanism Testing.......................................................................C-6
LIST OF TABLES
TABLE NO. TITLE
1-1 Masses Used to Test Discovery Balance..............................................................1-3
1-2 Discovery Balance Model Specifications...............................................................1-4
2-1 Balance Will Not Turn On......................................................................................2-2
2-2 Balance Does Not Respond to Front Panel Controls............................................2-3
2-3 No Display or Partial Display.................................................................................2-3
2-4 Balance Cannot Calibrate Using External Weights...............................................2-4
2-5 Balance Cannot Calibrate Internally......................................................................2-5
2-6 Error Codes...........................................................................................................2-6
3-1 Display Assembly Parts List..................................................................................3-5
4-1 Discovery Test Masses.........................................................................................4-5
4-2 COM1 Interface Pin Connections..........................................................................4-7
4-3 RS232 Command Table........................................................................................4-8
5-1 Parts List for Discovery Housing...........................................................................5-1
5-2 Parts List for Discovery Display Assembly............................................................5-2
5-3 List of Internal Parts Outside Load Cell.................................................................5-3
5-4 List of Discovery Load Cell Parts ..........................................................................5-4
LIST OF ILLUSTRATIONS
FIGURE NO. TITLE
1-1 Service Toolset, Part No. 80030340 .....................................................................1-2
3-1 Breeze Ring, Breeze Ring Base, Grommet and Pan
removed from Discovery Balance .........................................................................3-1
3-2 Removing Discovery Balance back cover.............................................................3-2
3-3 Balance with back cover removed.........................................................................3-2
3-4 Scale bottom, showing Draft Shield Assembly......................................................3-3
3-5 Discovery Balance with cover removed ................................................................3-4
3-6 Keyway hole on cover guided over cone-shaped brass screw heads...................3-4
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TABLE OF CONTENTS
LIST OF ILLUSTRATIONS (Cont.)
FIGURE NO. TITLE Page No.
3-7 Scale drawing of Discovery Balance Display Parts...............................................3-5
3-8 Removing screws to separate Display Housing from bottom of balance ..............3-6
3-9 Display Balance Load Cell Cover..........................................................................3-7
3-10 Discovery Balance Printed Circuit Board (PCB)....................................................3-8
3-11 EEProm chip, next to battery on main PCB ..........................................................3-8
3-12 PCB Cover has alternating teeth to secure it to the Mounting Plate .....................3-9
3-13 Removing Display Cable Shield Plate.................................................................3-10
3-14 The InCal Weight Cover sits beneath the Display Cable Shield Plate................3-11
3-15 Weights and Weight Holders can be removed,
but should only be handled while wearing a clean glove ....................................3-11
3-16 InCal Weight hardware with Weights and Weight Holders removed.
Weight Arms with black tips are on either side of the Cantilever Arm.................3-12
3-17 Calibration Motor Assembly, installed to the right of the Load Cell.....................3-13
3-18 Calibration Motor Assembly, closeup, showing screws that secure it.................3-13
3-19 Calibration Motor Assembly ................................................................................3-14
3-20 Calibration Motor close-up, showing cam in rest position...................................3-14
3-21 Removing Display Cable Shield Plate.................................................................3-15
3-22 The InCal Weight Cover sits beneath the Display Cable Shield Plate................3-16
3-23 Removing Weights and Weight Holders, while wearing a clean glove................3-16
3-24 Lifting off the PCB and its Mounting Plate from the Load Cell ............................3-17
3-25 Lifting off Load Cell Cover...................................................................................3-17
3-26 Load Cell with cover removed.............................................................................3-18
3-27 Removing Cantilever Arm from Load Cell...........................................................3-18
3-28 Bottom Housing of Load Cell...............................................................................3-18
3-29 Load Cell chassis, with keyway position highlighted...........................................3-19
3-30 Load Cell removed..............................................................................................3-19
3-31 Removing screws from Load Cell top Cover.......................................................3-20
3-32 Load Cell with top cover removed.......................................................................3-20
3-33 Removing screws from Load Cell bottom Cover.................................................3-20
3-34 Load Cell with bottom cover removed.................................................................3-20
3-35 Screws on bottom Flexure Arm assembly...........................................................3-21
3-36 Screws on top Flexure Arm assembly.................................................................3-21
3-37 Service Toolset, Part No. 80030340 ...................................................................3-22
3-38 Brass Fixture inserted part way under the Load Cell’s Hanger...........................3-22
3-39 Brass Fixture fully inserted under the Load Cell’s Hanger..................................3-22
3-40 Thumb screws and Hanger on top of Load Cell..................................................3-23
3-41 Screws securing Load Flexure to Hanger on top of Load Cell............................3-23
3-42 Load Cell with Load Flexure, 2 screws and 4 washers removed ........................3-24
3-43 Flexures can be removed from Flexure Arm
after removing Flexure Arm from Load Cell frame ..............................................3-24
3-44 Removing the top Flexure Arm............................................................................3-24
3-45 Solder points connecting fine wire to Load Cell PCB..........................................3-25
3-46 Lifting Ratio Beam to insert Brass Rod ...............................................................3-26
3-47 Brass Rod installed .............................................................................................3-26
3-48 Screwing in Threaded Rod on front of Load Cell ................................................3-26
3-49 Removing screws from PCB. (Note stepped washer under rear screw).............3-27
3-50 Magnet Cover without PCB.................................................................................3-27
3-51 Solder points on top of Load Cell PCB................................................................3-27
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TABLE OF CONTENTS
LIST OF ILLUSTRATIONS (Cont.)
FIGURE NO. TITLE Page No.
3-52 Solder points on bottom of Load Cell PCB..........................................................3-27
3-53 Up/Down Stop Plate............................................................................................3-28
3-54 Removing Temperature Conductor.....................................................................3-28
3-55 Removing screws that secure the Magnet Cover................................................3-28
3-56 Lifting off the Magnet Cover................................................................................3-28
3-57 Removing Thumb screws that hold Hanger in place...........................................3-29
3-58 Load Cell without Hanger and Brass Fixture.......................................................3-29
3-59 Screws on each side of yoke holding Ratio Beam must be removed .................3-29
3-60 Ratio Beam, removed from Load Cell .................................................................3-30
3-61 Magnet gap and Temperature Sensor Tube should be
carefully examined for dust and debris................................................................3-30
3-62 Coil Assembly should be carefully examined and cleaned .................................3-30
3-63 Yoke of Ratio Beam must align with frame of Load Cell .....................................3-31
3-64 Installing Ratio Beam with hole centered over the Temperature Sensor Tube...3-31
3-65 Yoke aligned with frame side-to-side, and flush with frame on front...................3-32
3-66 Centering Pin goes into Temperature Sensor Tube in middle of Magnet ...........3-33
3-67 Hanger installed, with Brass Fixture and Brass Brackets....................................3-34
3-68 Magnet Cover has oblong hole that clears Ratio Beam’s stop tab......................3-35
3-69 Inserting screws to secure the Magnet Cover.....................................................3-35
3-70 Inserting the Temperature Conductor in the middle of the Magnet Cover...........3-35
3-71 The Temperature Conductor groove should line up with the two Screws...........3-35
3-72 Up/Down Stop Plate which rests on Magnet Cover ............................................3-36
3-73 Up/Down Stop Plate inserted over Ratio Beam tab
and PCB screw receptacle on Magnet Cover .....................................................3-36
3-74 Load Cell PCB is secured with 2 screws (with Step Bushing on the back).........3-36
3-75 Fine wires must have smooth arc for the balance to function properly...............3-37
3-76 Load Cell should rest on Threaded Rod, and base of frame...............................3-38
3-77 Installing the bottom Flexure Arm........................................................................3-39
3-78 Top Flexure Arm Assembly, with Flexure screw heads facing outward..............3-39
3-79 Installing the upper Flexure Arm .........................................................................3-39
3-80 Load Flexure, aluminum washers, steel washers and screws............................3-40
3-81 Load Flexure on top of Hanger, with elongated screw hole at bottom................3-40
3-82 Hanger with Thumb screws removed..................................................................3-41
3-83 Pushing Brass Fixture from grooved side ...........................................................3-41
3-84 Pulling Brass Fixture out from square side..........................................................3-41
3-85 Note stops on sides of bottom Load Cell Cover..................................................3-42
3-86 Tightening screws on bottom Load Cell Cover....................................................3-42
3-87 Top Load Cell Cover rests flush against bottom cover........................................3-43
3-88 Tightening screws on top Load Cell Cover..........................................................3-43
3-89 If Hanger moves smoothly, assembly is successful............................................3-44
3-90 Load Cell Chassis with keyway at point of triangle .............................................3-45
3-91 Three screws on bottom that secure the Load Cell to the Chassis.....................3-45
3-92 Cantilever Arm in correct position .......................................................................3-45
3-93 Replacing Load Cell Cover..................................................................................3-46
3-94 Load Cell with Cover in proper position, cables resting in notches.....................3-46
3-95 Placing PCB Mounting Plate on Load Cell..........................................................3-47
3-96 Stand-off screws secure PCB Mounting Plate ....................................................3-47
3-97 Installing Weights and Weight Holders................................................................3-48
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TABLE OF CONTENTS
LIST OF ILLUSTRATIONS (Cont.)
FIGURE NO. TITLE Page No.
3-98 Proper position of InCal Weight Cover................................................................3-48
3-99 Inserting screws in Display Cable Shield Plate,
after checking that Pan Socket is centered in hole in middle of Plate.................3-49
3-100 Correct position of Display Cable under Display Cable Shield Plate ..................3-49
3-101 Securing PCB Cover...........................................................................................3-50
4-1 LCD Full Display for Discovery Balance................................................................4-1
4-2 Holes in back cover must be popped out to insert Allen Keys ..............................4-3
4-3 Ohaus engineer demonstrates adjusting Off-Center Load....................................4-3
4-4 Allen key rotation directions needed for back-edge-heavy,
back-edge-light, right-edge-heavy and right-edge-light conditions........................4-4
4-5 Com 1 Connector, as it appears on balance’s back cover....................................4-7
4-6 AC Adapter Cord...................................................................................................4-9
5-1 Discovery Balance Housing ..................................................................................5-1
5-2 Discovery Balance Display Assembly...................................................................5-2
5-3 Internal Parts Outside Load Cell ...........................................................................5-3
5-4 Discovery Balance Load Cell Parts.......................................................................5-4
A-1 Calibration Menu flow: Press No until the desired option appears, then Yes. ..... A-1
B-1 Service Calibration Menu Sequence.................................................................... B-1
C-1 Com Port Configuration menu..............................................................................C-1
C-2 Software Service Tool’s Restore EEProm tab......................................................C-2
C-3 Software Service Tool’s Replace Load Cell tab...................................................C-3
C-4 Software Service Tool’s Replace PCB tab...........................................................C-4
C-5 Software Service Tool’s Download Software tab .................................................C-5
C-6 Software Service Tool’s Diagnostics tab..............................................................C-6
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TABLE OF CONTENTS
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CHAPTER 1 INTRODUCTION
1.1 INTRODUCTION
This service manual contains the information needed to perform routine maintenance and
service on the Discovery Balances. The contents of this manual are contained in five chapters,
three appendixes and are listed as follows:
Chapter 1 Introduction – A guide service facilities, tools, test equipment, calibration masses
and specifications.
Chapter 2 Diagnosis – A diagnostic guide for troubleshooting, and an error code table.
Chapter 3 Repair Procedures – Disassembly/assembly, repair and replacement procedures.
Chapter 4 Testing – An operational test, segment display tests and performance tests.
Chapter 5 Parts Lists and Diagrams – Exploded view drawings and parts lists for Discovery
Balances.
Appendix A Standard Calibration – Procedures for Automatic Internal Calibration, Span
Calibration, Calibration Testing, and Calibration Adjustment.
Appendix B Service Calibration – Procedures for Service Calibration.
Appendix C Discovery Service Tool Instructions – Used to update software, restore
EEPROM data, install a new Main Printed Circuit Board and install a new Load Cell.
Before servicing the balance, you should be familiar with the Instruction Manual (Part Number
80104130) which is packed with every balance. The procedures in this manual assume the
technician performing them has a working knowledge of standard hand tools and the repair of
precision instruments.
1.2 SERVICE FACILITIES
To service a balance, the service area should meet the following requirements:
•Should be temperature controlled and meet the balance specifications for temperature
environmental requirements. See specifications for temperature ranges of the various
models.
•Must be free of vibrations such as fork lift trucks close by, large motors, etc.
•Must be free of air currents or drafts from air conditioning/heating ducts, opens windows,
people walking by, fans, etc.
•Area must be clean and air must not contain excessive dust particles.
•Work surface must be stable and level.
•Work surface must not be exposed to direct sunlight or radiating heat sources.
•Use an approved Electro-Static Device.
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CHAPTER 1 INTRODUCTION
1.3 SPECIAL TOOLS AND TEST EQUIPMENT REQUIRED
To properly service the Discovery Balances, certain Ohaus special tools and test items are
required in addition to standard electronic tool kits. These items are listed as follows:
1. Alternate voltage Power Adapter if local power requirements do not match balance
Adapter voltage ratings.
2. A PC running Microsoft Windows NT 4.0 or later, or Microsoft Windows 98 or later.
3. Discovery Instruction Manual, Part No. 80104130.
4. MFR Service Toolset, Part No. 80030340.
Figure 1-1. Service Toolset, Part No. 80030340.
5. RS232 Cable – Balance to PC P/N 80500525.
6. Standard Electronics Tool Kit.
7. Digital Voltmeter (DVM) Input impedance of at least 10 megohms in the 1 Volt DC
position.
8. Masses as shown in Table 1.4. These masses are available from any Ohaus dealer.
9. Discovery Software Service Tool, P/N 80104129
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CHAPTER 1 INTRODUCTION
1.4 TEST MASSES REQUIRED
The masses required to test the Discovery Balances must meet or exceed the requirements of
the Class specified. The calibration points for the Discovery Models are listed in Table 1-1.
Use the minimum number of masses to total the calibration point value.
Table 1-1. MASSES USED TO TEST DISCOVERY BALANCES
SPAN CALIBRATION POINTS
WEIGHT CLASS MODEL CAPACITY (g) DEFAULT ALTERNATE
ASTM OIML CAL POINTS (g) CAL POINTS (g)
Class 1 E1 DV114C 110 100 50
Class 1 E1 DV214C 210 200 100
Class 1 E1 DV314C 310 300 100, 200
Class 1 E1 DV215CD 81/210 200 100
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CHAPTER 1 INTRODUCTION
1.5 SPECIFICATIONS
Specifications for the Discovery Balances are listed in Table 1-2. After a balance has been
serviced, it must meet the specifications listed in the table.
Table 1-2. DISCOVERY BALANCE MODEL SPECIFICATIONS
Model Number DV 114C DV 214C DV 314C DV215CD
Capacity (g) 110 210 310 81/210
Readability (mg) 0.1 0.01/0.1
Repeatability
(Std.dev.) (mg) 0.1 0.2 0.02/0.1
Linearity (mg) ±0.2 ±0.5 ±0.03/0.2
Off Center Load
½ cap, ½ distance ± 0.3 mg
Weighing Units mg, g, oz, ct, dwt, ozt, GN, taels (3), momme, Custom unit
Application Modes Weighing, Parts Counting, Percent Weighing,
Checkweighing, Animal/Dynamic Weighing, G/N/T,
Totalization, High Point, Density, Statistics, Pipette
Tare Range To Capacity by Subtraction
Stabilization Time(s) 4 8 12/5
Power
Requirements External Adapter, 100-120VAC 1A, 220-240VAC 1A, 50/60Hz
Calibration Automatic internal and manual external
Display Type 2-line Alphanumeric backlit LCD Display with Text Prompts
Display Size (in/cm) 4 x 1/ 10 x 2.5
Pan Size (Diameter)
(in/cm) 3.5/9
Free Height above
Pan (in/cm) 9.5/24
Dimensions
W x H x D (in/cm) 7.9 x 11.8 x 18/20 x 30 x 45.7
Net Weight (lb/kg) 22.5/10.2
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CHAPTER 2 DIAGNOSIS
2.1 TROUBLESHOOTING
This section of the manual contains troubleshooting information. Information is contained to
isolate specific problems using Table 2-1 – 2-5, Diagnostic Guide, and Table 2-6, Error Codes.
Follow all directions step by step. Make certain that the work area is clean. Handle balance
components with care. Use appropriate Electro-Static Device.
2.2 DIAGNOSTIC GUIDE
Tables 2-1 – 2-5 are a Diagnostic Guide designed to help locate the problem area quickly and
easily. The probable causes are listed with the most common cause first. If the first remedy
does not fix the problem, proceed to the next remedy. Before attempting to repair the balance,
read all chapters of this manual to be familiar with the balance components and operation.
2.2.1 Diagnosis
1. Isolate and identify the symptom
2. Refer to Tables 2-1 – 2-5 Diagnostic Guide and locate the symptom. Also consult the
Error Code Table for solutions to specific codes.
3. Follow the suggested remedies in the order they appear.
4. Perform the indicated checks, or see the appropriate section of the manual.
5. Repair or replace the defective section of the balance.
NOTE:
If more than one symptom is observed, approach one area at a time,
and remember that the symptoms may be interrelated.
If a problem arises that is not covered in this manual, contact Ohaus Corporation for further
information.
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CHAPTER 2 DIAGNOSIS
TABLE 2-1. BALANCE WILL NOT TURN ON
SYMPTOM PROBABLE CAUSE REMEDY
Balance will not turn on.
Main power source is off.
On/Zero Off switch
defective or actuating
fingers on top housing
defective.
Main PC Board is
defective.
Check the main power
source outlet for proper
voltage.
See Table 2-2.
If the balance fails to turn on
and On/Zero Off switch is
OK, the Main PC Board is
defective and should be
replaced.
->Main Printed Circuit Board
Removal & Replacement
3.1.3
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CHAPTER 2 DIAGNOSIS
TABLE 2-2. BALANCE DOES NOT RESPOND TO FRONT PANEL CONTROLS.
SYMPTOM PROBABLE CAUSE REMEDY
Balance does not
respond to front panel
controls.
PC board switch or
actuating fingers on top
housing are defective.
Display PC Board is
defective.
Main PC Board is
Defective
Open the balance. (Refer to
Section 3.1.1. Using an
Ohmmeter, measure the
resistance between the pins of
the ON/Zero Off switch. It should
be open. Press the switch
through the top housing and
check that the resistance is zero.
Check each switch in a similar
manner. If continuity is not
present on a particular switch,
replace the affected switch or
actuator.
If the balance fails to turn on and
On/Zero Off switch is OK, the
Display PC Board may be
defective and should be replaced.
->Display PCB Repair &
Replacement 3.1.2
If Balance fails to turn on and
Display PCB has been replaced
then the Main PCB should be
replaced.
->Main PCB Removal &
Replacement 3.1.3
TABLE 2-3. NO DISPLAY OR PARTIAL DISPLAY
SYMPTOM PROBABLE CAUSE REMEDY
Display is not on or
partial characters are
displayed.
Display PC Board is
defective. The Display PC Board is replaced as a whole assembly. Check
procedures in Table 2-1 first and
verify that other problems do not
exist.
->Display PCB Removal &
Replacement 3.1.2.
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CHAPTER 2 DIAGNOSIS
TABLE 2-4. BALANCE CANNOT CALIBRATE USING EXTERNAL WEIGHTS
SYMPTOM PROBABLE CAUSE REMEDY
Balance can be turned on
but will not calibrate
manually.
Incorrect weights.
Balance is set for Legal For
Trade operation.
Balance not level.
Balance is unstable.
Verify that proper weights
are used.
Set the Setup Menu Legal
For Trade setting to Off.
(See Instruction Manual,
Sections 3.7.12 & 3.8.)
Level balance.
Perform Automatic Internal
Calibration.
->Appendix A.1.
If the balance fails to
calibrate properly, enter the
service mode (Appendix B)
and perform a Span
Calibration. If this fails,
check the InCal Weight
Assembly and the Load
Cell Assembly (Section
3.1.5 – 3.2.7). Ensure that
all parts are clean and
properly aligned.
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CHAPTER 2 DIAGNOSIS
TABLE 2-5. BALANCE CANNOT CALIBRATE INTERNALLY
SYMPTOM PROBABLE CAUSE REMEDY
Balance can be turned on
but will not calibrate using
internal calibration.
Balance may be
unstable.
The InCal Weight
Hardware may be dirty,
mis-aligned or
defective.
Calibration Motor
Assembly may be
defective
Main PC Board may be
defective.
Load Cell PCB is
defective
Level the balance using leveling
feet on rear of chassis, together
with leveling bubble, just inside
the left Door Side Draft Shield.
Disassemble the InCal Weight
Hardware and test it.
->InCal Weight Hardware
Disassembly & Testing 3.1.4.
If there are problems with the
Weight Arm movements, check
the Calibration Motor, and
replace if necessary.
->Removing & Replacing
Calibration Motor Assembly
3.1.5.
Verify that all other functions
are operational. If not, the Main
PC board may be defective.
->Main PCB Removal &
Replacement 3.1.3.
Replace Load Cell PCB.
(See p. 3-27.)
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CHAPTER 2 DIAGNOSIS
2.3 ERROR CODES
The following table lists error codes, possible causes and remedies. If the problem persists,
contact Ohaus Corporation. TABLE 2-6. ERROR CODES
ERROR CODE PROBABLE CAUSE REMEDY
Error 7.0
Unstable weight reading
when defining the reference
weight
Eliminate vibration and
drafts.
Error 8.0 Weight reading below
Power On/Zero limit. Put pan on balance.
Error 8.1 Weight reading exceeds
Power On/Zero limit. Clear pan
Error 8.3 Weight reading exceeds
overload limit. Clear pan.
Error 8.4 Weight reading below
underload limit. Put pan on balance.
Error 9.0 Internal fault. Restore EEPROM data,
using Software Service
Tool. (See Appendix C.1).
Replace Main PCB.
Error 9.5 Production calibration not
present. Perform Service Calibration (See Appendix B).
Error 9.8 User calibration data not
present. (Required for
LFT ON only)
Calibrate balance.
Error 53 EEPROM checksum error. Cycle power on, off. If
balance fails to operate,
restore EEPROM data.
LOW REF WT Average piece weight too
small. (Warning only –
count will continue.)
See Instruction Manual for
more detail.
REF WT Err Reference weight too small.
The weight on the pan is
too small to define a valid
reference weight.
Increase sample size.
Busy (during tare, zero, printing,
calibration, etc.) Wait until completion.
- - - - - - - - - - - Unstable weight reading If balance is level, in
appropriate environment,
repair Load Cell.
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